diff --git a/ass_mp.c b/ass_mp.c
index 31acb521b8..364adafd64 100644
--- a/ass_mp.c
+++ b/ass_mp.c
@@ -154,7 +154,7 @@ static int check_duplicate_plaintext_event(ASS_Track *track)
  * note: assumes that subtitle is _not_ fps-based; caller must manually correct
  *   Start and Duration in other case.
  **/
-int ass_process_subtitle(ASS_Track *track, subtitle *sub)
+static int ass_process_subtitle(ASS_Track *track, subtitle *sub)
 {
     int eid;
     ASS_Event *event;
diff --git a/ass_mp.h b/ass_mp.h
index 0694426898..2966f9527a 100644
--- a/ass_mp.h
+++ b/ass_mp.h
@@ -44,7 +44,6 @@ extern char *ass_styles_file;
 extern int ass_hinting;
 
 ASS_Track *ass_default_track(ASS_Library *library);
-int ass_process_subtitle(ASS_Track *track, subtitle *sub);
 ASS_Track *ass_read_subdata(ASS_Library *library, sub_data *subdata,
                             double fps);
 ASS_Track *ass_read_stream(ASS_Library *library, const char *fname, char *charset);
diff --git a/sub/sd_ass.c b/sub/sd_ass.c
index a25d50a805..5eae2ebc28 100644
--- a/sub/sd_ass.c
+++ b/sub/sd_ass.c
@@ -19,6 +19,7 @@
 #include <stdlib.h>
 #include <ass/ass.h>
 #include <assert.h>
+#include <string.h>
 
 #include "talloc.h"
 
@@ -27,11 +28,20 @@
 #include "libvo/sub.h"
 #include "ass_mp.h"
 #include "sd.h"
+#include "subassconvert.h"
 
 struct sd_ass_priv {
     struct ass_track *ass_track;
+    bool incomplete_event;
 };
 
+static void free_last_event(ASS_Track *track)
+{
+    assert(track->n_events > 0);
+    ass_free_event(track, track->n_events - 1);
+    track->n_events--;
+}
+
 static void init(struct sh_sub *sh, struct osd_state *osd)
 {
     struct sd_ass_priv *ctx;
@@ -57,28 +67,71 @@ static void init(struct sh_sub *sh, struct osd_state *osd)
 static void decode(struct sh_sub *sh, struct osd_state *osd, void *data,
                    int data_len, double pts, double duration)
 {
+    unsigned char *text = data;
     struct sd_ass_priv *ctx = sh->context;
+    ASS_Track *track = ctx->ass_track;
 
     if (sh->type == 'a') { // ssa/ass subs
-        ass_process_chunk(ctx->ass_track, data, data_len,
+        ass_process_chunk(track, data, data_len,
                           (long long)(pts*1000 + 0.5),
                           (long long)(duration*1000 + 0.5));
-    } else { // plaintext subs
-        if (pts != MP_NOPTS_VALUE) {
-            subtitle tmp_subs = {0};
-            if (duration <= 0)
-                duration = 3;
-            sub_add_text(&tmp_subs, data, data_len, pts + duration);
-            tmp_subs.start = pts * 100;
-            tmp_subs.end = (pts + duration) * 100;
-            ass_process_subtitle(ctx->ass_track, &tmp_subs);
-            sub_clear_text(&tmp_subs, MP_NOPTS_VALUE);
-        }
+        return;
     }
+    // plaintext subs
+    if (pts == MP_NOPTS_VALUE) {
+        mp_msg(MSGT_SUBREADER, MSGL_WARN, "Subtitle without pts, ignored\n");
+        return;
+    }
+    long long ipts = pts * 1000 + 0.5;
+    long long iduration = duration * 1000 + 0.5;
+    if (ctx->incomplete_event) {
+        ctx->incomplete_event = false;
+        ASS_Event *event = track->events + track->n_events - 1;
+        if (ipts <= event->Start)
+            free_last_event(track);
+        else
+            event->Duration = ipts - event->Start;
+    }
+    // Note: we rely on there being guaranteed 0 bytes after data packets
+    int len = strlen(text);
+    if (len < 5) {
+        // Some tracks use a whitespace (but not empty) packet to mark end
+        // of previous subtitle.
+        for (int i = 0; i < len; i++)
+            if (!strchr(" \f\n\r\t\v", text[i]))
+                goto not_all_whitespace;
+        return;
+    }
+ not_all_whitespace:;
+    char buf[500];
+    subassconvert_subrip(text, buf, sizeof(buf));
+    for (int i = 0; i < track->n_events; i++)
+        if (track->events[i].Start == ipts
+            && (duration <= 0 || track->events[i].Duration == iduration)
+            && strcmp(track->events[i].Text, buf) == 0)
+            return;   // We've already added this subtitle
+    if (duration <= 0) {
+        iduration = 10000;
+        ctx->incomplete_event = true;
+    }
+    int eid = ass_alloc_event(track);
+    ASS_Event *event = track->events + eid;
+    event->Start = ipts;
+    event->Duration = iduration;
+    event->Text = strdup(buf);
+}
+
+static void reset(struct sh_sub *sh, struct osd_state *osd)
+{
+    struct sd_ass_priv *ctx = sh->context;
+    if (ctx->incomplete_event)
+        free_last_event(ctx->ass_track);
+    ctx->incomplete_event = false;
 }
 
 static void switch_off(struct sh_sub *sh, struct osd_state *osd)
 {
+    reset(sh, osd);
     osd->ass_track = NULL;
 }
 
@@ -93,6 +146,7 @@ static void uninit(struct sh_sub *sh)
 const struct sd_functions sd_ass = {
     .init = init,
     .decode = decode,
+    .reset = reset,
     .switch_off = switch_off,
     .uninit = uninit,
 };